Imparting and erasing shape in cotton textiles



United States Patent O Int. Cl. D06m 1/10, 13/38 US. Cl. 8-116.2 15 Claims ABSTRACT OF THE DISCLOSURE Quaternary ammonium hydroxide cellulose plasticizing agents are applied to cellulosic textile materials either to enhance the durability of configurations, e.g., crimps, twists, creases, pleats, etc., mechanically imparted thereto or to remove said configurations, depending upon conditions. The modified materials may be after-treated with cross-linking agents.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States.

GENERAL FEATURES This invention relates to a method of imparting durable shape to cotton and other cellulosic textiles and erasing this shape at will. More specifically the invention relates to a method of imparting and removing durable crimp, twist, and coiling in cotton yarn, and permanent creases, pleats, and roundness in cotton fabrics. By the process of this invention the shape imparted to the textile is made resistant to removal by steeping in boiling water, by ironing, by laundering, and by mechanical deformation or tensioning in either the wet or dry condition of the textile. Yet the shape so fixed may readily be altered or removed by reapplication of the process disclosed herein.

The shaping of cotton textiles is commonly accomplished by placing the yarn or fabric in the desired conformation and while mechanically holding it in this conformation, heating the textile with a cellulose crosslinking agent, together wtih a crosslinking catalyst which activates the crosslinking agent for chemical reaction with the cotton cellulose. Such shaping treatments are used in the crimping, twisting, and coiling of cotton yarns for the preparation of lofty and stretchable yarns. Such shaping treatments also have wide utility in fixing creases and pleats in cloth of fully fabricated garments, so that the final shape desired is the shape actually imparted.

It is well known that the cellulose crosslinking treatments conventionally used in imparting permanent crimp, twist, and creases to cotton have numerous disadvantages. The crosslinking of native cellulose greatly decreases its strength and abrasion resistance, thus drastically reducing the wear life of the textile material through roughening and tearing of garment edges, as well as splitting of "ice seams and creases. Textiles given cellulose crosslinking treatments show rapid and uneven wearing away of dyes, thus producing at the edges and raised areas of greater wear a frosted or whitened appearance. In addition, the shape fixed in cotton textiles by cellulose crosslinking processes cannot be removed or altered to meet changing requirements of the user.

OBJECTS OF THE INVENTION The main object of the present invention is to provide a method of imparting shape to textiles of fibrous unregenerated cellulose, such as cotton, which shape is resistant to removal by wetting, heating, and by mechanical tensioning applied when the textile is wet or when the textile is dry.

A second object of this invention is to provide a means of erasing or altering shape already imparted to cotton textiles by processes of this invention.

A third object of this invention is to provide a means of imparting durable shape to cotton textiles without loss of tensile strength and abrasion resistance in the shaped area of the textile.

A fourth object of this invention is to provide a means of imparting durable shape to cotton textiles without producing discoloration of the cotton.

A fifth object of this invention is to provide a chemical treatment for fixing shape in cotton textiles without the use of heat during application of the chemical treatment.

A sixth object of this invention is to provide a means of imparting durable shape to cotton textiles without changing the type of crystal lattice present in the cellulose. It is well known that the pliability rot resistance, stain resistance, and oxidation resistance of cotton can be adversely affected by changes in lattice type.

A seventh object of the present invention is to increase the effectiveness of cellulose crosslinking agents in impart ing dimensional stabilization to cotton textiles, to the extent that a very low degree of cellulose crosslinking applied subsequent to our treatment suffices to impart a high degree of dimensional stabilization,.thereby minimizing the loss of strength and abrasion resistance that occur during the cellulose crosslinking treatment.

An eighth object of this invention is to eliminate the need for acidic or alkaline catalysts while carrying out dimensional stabilization of cotton textileswith conventional cellulose crosslinking agents, thus eliminating cellulose degradation during such crosslinking treatments, and preventing the losses of strength and abrasion resistance caused by such catalysts at high temperature; I

Other objects of this invention will become apparent in the description that follows.

COMPARISON WITH PRIOR ART or peats are fixed and erased by heat, and thusare not durable to accidental contact with heated surfaces. The

degree of chemical substitution required is so great as to cause large changes in textile weight, thickness, stiffness,

and moisture absorption, as well as requiring slow and expensive batch processing of the textile.

Various swelling agents have previously been recommended for the shaping of cellulosic textiles, in most instances to form embossed or creped fabrics in which any subsequent mechanical tensions or stretching are borne by the flat, unembossed areas surrounding the spots actually treated. In such cases, the embossed areas do not need to be resistant to mechanical tensioning and deformation while wet or While dry, and no appreciable effort has previously been made to evaluate such swelling treatments in this respect. As will be seen in the examples to follow, shape-imparted to cotton using such common swelling agents as sulfuric acid, zinc chloride and sodium hydroxide is not durable to repeated tensioning during successive 'wetting and drying cycles.

Reeves and Mack (Am. Dyestuff Reptr., 48, No. 21, 43-46, 50 (1959)) used a combination of heat and sodium hydroxide to set and erase creases in cotton fabric. Although durable creases were obtained, the fabric showed a loss of breaking strength and a yellow discoloration due to degradation of the cellulose of the fabric by hot alkali. Moreover, vat dyed fabric in some cases showed a change in hue due to the effect of hot alkali in altering the dye. Reeves and Mack further reported that when 28% benzyltrimethylammonium hydroxide or cuprammonium hydroxide were applied in this manner, the quaternary ammonium hydroxide and the cuprammonium hydroxide in water solutions were somewhat less effective than the sodium hydroxide.

Karrholm and Asnes (Textile Research J., 34, 220-235 (1964)) reported experiments with aqueous sodium hydroxide and aqueous zinc chloride at 20 and 92 C. in fixing twist in yarn. They showed (in their Table III) that the two agents were nearly equal in their effect, and were more effective at the higher temperature. Even at the higher temperature, the helix of cotton yarn lost practically all its twist if straightened after the swelling agent had been rinsed out, but prior to yarn drying (condition 4 of their FIGS. 15 and 16). Considerable twist was retained if the yarn was straightened during swelling but subsequently kept coiled during rinsing and drying (condition 2). It is clear that fixation of the coiling depended in their process on having the yarn coiled as it was being deswelled :by drying (p. 231). Such a process of dryinginto-shape operates partly by rearranging the hydrogen bonds between cellulose chains, and the effects so obtained are of low durability to washing, particularly if the washing is done in hot water. The shapes imparted to textiles by our processes are durable to steeping of the textile in boiling water. This shows that our process does not owe its effects merely to rearrangement of hydrogen bonds in cotton cellulose, which bonds are unstable to moisture and heat.

Various cellulose solvents such as cupriethylenediamine have previously been proposed as agents for fixing shape in cotton textiles. By treatment of the textile material for sufficiently short periods, the cellulose solvent is said to decrystallize the cellulose without greatly disrupting the fiberstructure. As will be seen from the example to follow, the use of'cupriethylenediamine solutions in low concentrations to impart shape leads to poor durability of the .the' tshape to tensioning during repeated wetting and drying. At higher concentrationswhich might have been expected to give improved durability of textile shape, the reagent caused partial solution of the cellulose, resulting in the fusing together of yarns to the great impairment of the textile properties of the cotton.

The present invention does not utilize processes of swelling, shaping,- rinsing, and drying-into-shape already described, nor does it cause solution and dispersal of any p'art'of'the cotton'fibers under the conditions of processing. 'The invention is based on the discovery that certain quaternary ammonium hydroxides convert solid cellulose to -a gel-like, plastic form, in whi h each fi er re a ns it outer primary wall intact, thereby preserving the identity of each fiber and yarn, and enabling the cellulosic textile to be shaped While retaining its fibrous spun, woven or knitted structure. The fibers remain separate and are not fused together. As a result, the textile yarn and fabric retain their suppleness, air permeability and moisture absorption after the quaternary ammonium hydroxide is removed by washing. Quite unexpectedly it is found that the shape in which the textile is held, while being wetted with the quaternary ammonium hydroxide and subsequently washed free of the quaternary ammonium hydroxide, is retained to a considerable degree through later drying, re-

'wetting and tensioning treatments. This durability of the imparted shape is achieved even if the textile is tensioned, straightened or deformed just after the quaternary ammonium hydroxide has been removed by washing but prior to removal of water by drying. Insthis respect the process of the present invention differs from all previously reported noncrosslinking treatments. Native cellulose so treated is moreover found to possess the cellulose I crystal lattice subsequent to treatment, while mercerized cellulose possesses the cellulose II lattice after treatment. Thus the type of crystal lattice possessed by the cellulose of the textile is unchanged by the processes of this invention.

DESCRIPTION OF SHAPING PROCESS The following sequence of steps constitutes the textile shaping process of our invention.

(a) Submitting the fibrous cellulosic textile to a desired conformation, and while maintaining the textile in said desired shape at room temperature for a minimal duration of time,

(b) Impregnating the fibrous cellulosic textile with an aqueous solution containing about from 33% to 60% by weight of a quaternary ammonium hydroxide of the structural configuration where R and R are selected from the group of radicals consisting of methyl, ethyl, phenyl, and benzyl, and R is selected from the group of radicals consisting of methyl, ethyl, and those having the structural configuration and R is selected from the group of radicals consisting of hydrogen and those having the structural configuration HoozH5-NoH2- C2Hb (0) Aging the wet impregnated fibrous cellulosic textile by allowing about from 1 to 60 minutes of time to elapse while maintaining the said shape of the textile at room temperature, and

(d) Washing and drying the textile. 1

Departure from this sequence, by wetting the cotton textile with the quaternary ammonium hydroxide prior to mechanically fixing it in the shape to be imparted, greatly diminishes the degree to Which the shape is retained after the quarternary ammonium hydroxide is washed from the textile.

The above sequence is applicable to the treatment of spun, woven and knitted textiles of fibrous, unregenerated cotton in the form of yarn, thread and fabric. It is not applicable to thin nonwoven webs such as thin-sheets of paper, which lack sufiicient interfiber cohesion to hold together when plasticized with the quaternary ammonium hydroxides employed in this process. The above processes of our invention are applicable not only to textiles of native cotton, but also to textiles of mercerized cotton and textiles of cotton in which the cellulose has been etherified to theextent of not more than one alkyl or aralkyl group introduced for every three anhydroglucose units of the cellulose chains. Methylated and benzylated cottons are particularly suited to treatment by the present processes, and the shapes imparted to these etherified cottons are even more resistant to the effects of wetting with water than is the case with native cotton.

The methods of carrying out step (a) in our process, which step comprises mechanically fixing cotton textiles in the shape to be imparted, are well known to the industry and vary with the type of textile and the shape to be imparted. In the coiling or falsetwisting of yarn, the yarn may be wound in a tight coil about a rod or mandrel, the two ends of the yarn being tied to the rod to prevent shrinkage of the yarn. The tighter the coiling desired, the narrower is the diameter of the rod selected. The rod and its surrounding coil may then be immersed in the solution of quarternary ammonium hydroxide to carry out step (b) of our process.

In the creasing of fabric, the crease may be impressed in the desired position by pressure or by ironing, and the fabric, when folded at the crease, may be clamped between two flat plates with the edge of the crease even with the edges of the plates. The edge of the crease may then be wetted with the solution of quaternary ammonium hydroxide by dipping. If desired, a third plate may be inserted between the two layers of the folded fabric with the edge of this plate against the inside of the crease to prevent shrinkage during subseqeunt wetting with the quarternay ammonium hydroxide.

In the production of rounded or molded shapes, the fabric may be bound closely around the mold form and dipped in the quaternary ammonium hydroxide solution, which causes the fabric to shrink tightly about the form.

In carrying out step (b) of our process specified above, it is completely essential that the quaternary ammonium hydroxide be in aqueous solution. When applied in nonaqueous media, the quaternary ammonia hydroxide is without effect in imparting plasticity and shape to cotton. It is also essential that the quaternary ammonium hydroxide have a certain molecular size and configuration as indicated in the structures shown above. Simpler quaternary ammonium hydroxides such as tetramethylammonium hydroxide are ineffective, as will be seen in examples to follow.

The concentration of quaternary ammonium hydroxide used in step (b) of the above sequence is critical to the success of the process, and the optimum concentration varies to a moderate extent with the shape being imparted. Typical of the quaternary ammonium hydroxides effective in the present invention is benzyltrirnethylammonium hydroxide. It is found that a concentration of this reagent as low as by weight is without effect in imparting yarn twist or coiling durable to subsequent tensioning during repeated wetting and drying; yet a concentration of is highly effective. At concentrations as high as of this quaternary ammonium hydroxide, a considerable stiffness is imparted to the treated portion of the textile, particularly if the treatment is continued for extended periods of time. This stiffening effect is useful in the creasing of stiff types of fabrics but is undesirable in imparting coiling or twist to yarn for the preparation of stretch yarns. To obtain a high degree of recoverable stretch in yarn requires that the yarn remain highly supple and flexible. Dibenzyldimethylammonium hydroxide and phenyldirnethylbenzylammonium hydroxide are somewhat more effective at a given normality than benzyltrimethylammonium hydroxide in the durable creasing of fabric, but are considerably less effective than the latter in imparting crimp, twist or coiling to yarn. The former hydroxides cause appreciable stiffening of the cotton, with increased durability and sharpness of creases in fabric but decreased elasticity in coiled yarns.

All of the above quaternary ammonium hydroxides are found to be about equally effective in fabric creasing, if compared at the same concentration in parts by weight. With p-xylylenebis(triethylammonium) hydroxide, which might have been expected to show a much greater cellulose plasticizing effect by virtue of being a dihydroxide, the effectiveness in fabric creasing is only moderately greater than for benzyltrimethylammonium hydroxide, and its effectiveness in yarn crimping or coiling is much less than for the latter compound, when compared at equal concentrations by weight. l,2-ethylenebis(benzyldimethylammonium) hydroxide was less effective than pxylylenebis(triethylammonium) hydroxide in fabric creasing, although it imparted fair durability to such creases.

The temperatures found preferable in carrying out steps (b), (c), and (d) of the above sequence are in the range of from about 15 C. to about 35 C. The use of much higher temperatures in steps (b) and (c) cause a yellow or brown discoloration of the cotton, excessive stiffness and hardness, and a decrease in yarn diameter. At temperatures above about 60 C., the quaternary ammonium hydroxides of the above structures undergo extensive decomposition, with loss of activity.

The time which should be allowed for step (c) varies somewhat with the quaternary ammonium hydroxide used, the concentration of the treating solution, the type of textile being treated and the type of shape being imparted. Less time is generally required in step (c) to set creases in cotton fabric than is required to set coiling or false twist in yarn. This is due in part to the fact that the fiber deformations imparted by creasing are very abrupt and can be readily set, whereas only slight changes in fiber shape and configuration are introduced by the coiling or twisting of yarn, and durably setting these slight deformations requires more complete plasticization of the cotton. Thus from about one to about ten minutes is ample for the treatment of creases with the quaternary ammonium hydroxide, with treating times of two to five minutes being preferred. From about ten to about sixty minutes is ample to set coiling in yarn with treating times of fifteen to thirty minutes being preferred. Longer times may be used in creasing or coiling treatments without marked adverse effects in the textile other than moderately increased stiffness, but there is no advantage in extending the time of treatment beyond that needed to obtain plasticization and subsequent reshaping of the fibers within the yarn or fabric structure.

REMOVAL OF IMPARTED SHAPE To erase or alter shape already imparted to cotton textile by our process merely requires reapplication of the shaping process described above. The textile is mechanically fixed in the new shape desired, is treated in the shaped area with a 33-60% aqueous solution of one of the above specified quaternary ammonium hydroxides, is allowed to stand for from one to sixty minutes, is washed free of the quaternary ammonium hydroxide, and is dried. Thus in erasing creases in fabric, it is desirable to spread the unfolded fabric as fiat as possible on a smooth surface. Ironing over the crease does not remove the crease but assists in realignment of the fibers. The area to be reshaped is wetted with the quaternary ammonium hydroxide, the fabric is allowed to stand for a period preferably in the range of five to ten minutes, and is washed. It may then be ironed dry, or dried by a stream of moving air.

IMPARTING SHAPE AND DIMENSIONAL STABILITY A further embodiment of the present invention is that the cotton textiles so treated are rendered especially suitable for subsequent application of cellulose crosslinking agents to impart shrinkage resistance, wrinkle resistance, wash-wear properties and still greater durability of previously imparted shape. Ordinarily, cellulose crosslinking agents must be heated with cotton in the presence of acidic or alkaline catalysts to obtain sufficient crosslinking to produce appreciable benefits. However, the high levels of crosslinking obtained in this way greatly decrease the strength and abrasion resistance of cotton, as already noted. Unexpectedly, it has been found that when even a very low degree of crosslinking is imparted to cotton textiles which have been previously treated by the processes of our invention, a large effect is produced by this slight crosslinking, in dimensionally stabilizing the textile. Consequently, it is found that no crosslinking catalyst whatever is needed during heat curing or the crosslinking agent on the cotton textile. The low degree of cellulose crosslinking imparted in the absence of cellulose crosslinking catalysts proves to be sufficient to achieve a large increase in durability of the crimp, coiling, twist and creases previously set in cotton textiles with quaternary ammonium hydroxides in the processes of our invention. The low degree of cellulose crosslinking obtained in the absence of acidic or alkaline crosslinking catalysts is demonstrated by the great swelling and ballooning the slightly crosslinked fibers undergo when wet with 0.5 M aqueous cupriethylenediamine solution. The level of crosslinking normally required for dimensional stabilization of cotton is so great as to suppress completely the swellability of the treated fiber in 0.5 M cupriethylenediamine solution. By eliminating the need for acidic or alkaline crosslinking catalysts, which at high temperature cause cellulose degradation and losses of strength and abrasion resistance, and by greatly decreasing the level of cellulose crosslinking needed to obtain the desired level of dimensional stability, the present invention results in higher retention of strength and abrasion resistance in the dimensionally stabilized cotton textile. Especially noteworthy and unexpected. is the degree of dimensional stabilization obtained, which is much greater than the sum of the effects produced separately by the quaternary ammonium hydroxide treatment and by the cellulose crosslinking treatment.

Only certain types of cellulose crosslinking agents may be used in the absence of crosslinking catalysts to impart dimensional stabilization to cotton textiles previously shaped and treated by our process with quaternary ammonium hydroxides. A first requirement of the cellulose crosslinking agent is that it polymerize readily when heated. Excluded are such cellulose crosslinking agents as bis(2-hydroxyethyl) sulfone, dichloromethane, or 1,3-dichloro-2-propanol, which give little or no thermally induced polymerization. A second requirement of the cellulose crosslinking agent is that its thermal polymers be of the three-dimensional, crosslinked type. Excluded are such cellulose crosslinking agents as N,N-dimethylolethyleneurea, commonly referred to as DMEU, which have but two reactive functional groups capable of undergoing condensation reactions. Bifunctional agents form linear polymers when heated. Such linearly polymerizing cellulose crosslinking agents are found to be almost completely inelfective in dimensionally stabilizing the cotton textiles shaped and treated with quaternary ammonium hydroxides by our process. When such an agent is heated with the shaped and treated textile in the absence of catalysts, it crosslinks the cotton to the extent of rendering fibers of the treated textile insoluble in 0.5 M cupriethylenediamine, yet produces almost no dimensional stabilization. Thus the dimensional stabilization produced by the cellulose crosslinking agents specified below is not explainable solely on the basis of cellulose crosslinking.

The cellulose crosslinking agents found effective in dimensionally stabilizing cotton textiles shaped and treated with quaternary ammonium hydroxides by our process are heat-polymerizable, water-soluble compounds containing in each molecule at least three functional groups selected from the class consisting of N-methylol groups and 1- aziridinyl groups. The said functional groups may be simple or may have substituents on their carbon atoms. For

example, the N-methylol group may be present as a 4- or 5-hydroxy-Z-imidazolidinone moiety. Typical examples are N,N',N" trimethylolmelamine, tris(1 aziridinyl phosphine oxide and 1,3-bis(hydroxymethyl)-4,5-dihydroxyl- 2-imidazolidinone.

In carrying out the cellulose crosslinking treatment, the cotton textile which has been mechanically confined to the desired shape, treated with the quaternary ammonium hydroxide, washed and dried as described above is, while still held in the desired shape, subsequently wetted with an aqueous solution containing about 2% to about 30% of the cellulose crosslinking agent. The wetted textile still held in the desired shape is then heated at temperatures of from about C. to about C. to drive otf water and induce polymerization as well as a low degree of cellulose crosslinking. Heating times of 2 minutes to 30 minutes are ample, the longer times being used at the lower temperatures. The textile may then be washed, dried and released from its mechanical holder, form or mold.

In applying cellulose crosslinking agents to creases which have previously been fixed in cotton fabric with the quaternary ammonium hydroxides specified herein, it is found advantageous to apply the crosslinking agent not only along the crease edge, but also to such areas of fabric beyond the crease edge as the quaternary ammonium hydroxide has penetrated by diffusion. With some types of fabric weaves, these areas become puckered and stiff on drying even though remaining smooth and supple when wet. The puckering and stiffening is due to the fact that the cotton fibers which have been greatly swollen by the quaternary ammonium hydroxide deswell and harden upon drying, and reswell and soften when rewet. Uneven swelling in the boundary region between treated and untreated areas results in pronounced puckering, particularly in twill and to a lesser degree in print cloth and sateen. It is unexpectedly found that application and curing of a cellulose crosslinking agent in the areas already treated with quaternary ammonium hydroxide removes the puckering and stiffening.

NOVEL MECHANISMS OPERATIV-E IN THE SHAPING PROCESS The mechanisms responsible for the processes of our inventions are indicative of the novelty of these processes. Two classes of swelling agents for cotton cellulose have previously been described in the textile literature: those which at a sufficiently high concentration are able to dissolve cotton fibers, and those which do not dissolve the fibers at any concentration. Only the former class of swelling agents have proven to be even moderately effective in rendering durable such shapes as are impressed in cotton textiles. It is evident that a high degree of decrystallization of the cellulose is required to obtain adequate plasticity, and only through cellulose solvation is this decrystallization obtained. The problem in using cellulose solvents is that most of these quickly dissolve the outer primary wall of the cotton fiber, permitting decrystallized cellulose in the fiber interior to disperse into the solvent medium. The immediate disappearance of the outer fiber walls can be readily seen microscopically, and when this occurs, the fiber structure and identify are destroyed. This causes adjacent yarns in fabric to fuse together, producing loss of such essential textile properties as softness, pliability, and porosity. When such a cellulose solvent is applied to a yarn which has been coiled to make the yarn elastic, fusing together of the adjacent windings of the coil by the solvent defeats the purpose of the coiling, by preventing elongation of the coiled yarns. Even if the time of treatment is kept short so that only the outer layers of the fibers are dissolved by the cellulose solvent, this fusion of adjacent yarns still occurs. If the time and solvent concentration are adjusted so that no solution of fibers occurs, the cellulose in the fiber interior is found not to be greatly plasticized, and little durability is imparted to the crimping, coiling, twist or pleats previously impressed in the 9 cotton textile. The above action of the common cellulose solvents upon the primary wall of a cotton fiber takes place rapidly at room temperature even in the absence of agitation, and is uncontrollable under the processing conditions of greatest practical interest.

Certain of the quaternary ammonium hydroxides used in our invention have previously been reported to dissolve cotton fibers suspended in them. What has not been reported previously is our observation that vigorous agitation of the suspension is required for dissolution of cotton fibers to occur in such quaternary ammonium hydroxides. Cotton fibers treated with the quaternary ammonium hydroxides requisite to our invention are rendered fairly transparent and highly swollen; yet in the absence of agitation the fibers retain their identity, and are readily distinguishable from one another by their sharp, distinct outlines, which are visible by microscopic examination even after the fibers have been in contact with the quaternary ammonium hydroxide for 48 hours at room temperature. In the. presence of vigorous agitation however cotton fibers are found to dissolve readily in these quaternary ammonium hydroxides within 10 minutes. The effectiveness of the above specified quaternary ammonium hydroxides therefore depends on their ability, under the conditions of our process, to decrystallize, solvate and plasticize cellulose within the cotton fibers, while leaving the outer essentially noncellulosic primary wall intact. The outermost portion of the primary Wall is known to be composed largely of waxes, pectins and proteins. The effect of fiber agitation in the presence of the swelling agent is to disrupt this confining wall. The uniqueness of these quaternary ammonium hydroxides as plasticizing agents for cotton is that their solvating action is confinable to the fiber interior, by avoidance of fiber agitation. The action of other commonly known cellulose solventsis not controllable in this way.

When a yarn spun of cotton fibers is treated while slack with the above specified quaternary ammonium hydroxides, it shrinks greatly, becoming translucent in appearance and gelatinous in texture. When this yarn is then restretched while wet with the quaternary ammonium hydroxide, it again regains its original opacity and firm, fibrous texture. If the yarn in this condition is again relaxed, it again shrinks and becomes translucent and gelatinous; and if restretched it again loses these properties.

A special situation exists however, if the cotton textile is mechanically shaped prior to the application of the quaternary ammonium hydroxide, and is mechanically confined to this imposed shape during application of the quaternary ammonium hydroxide. The great swelling and shrinkage normally produced in loose fibers by the quaternary ammonium hydroxide are prevented by the mechanical constraints previously imposed. The wetted constrained fibers are known to generate large internal forces within the fibers, and these forces cause plastic flow of the cellulose of the fibers in directions which relieve the imposed constraint. When the quaternary ammonium hydroxide is subsequently washed away from the yarn .or fabric, the plasticity of the cellulosic fibers is lost and the textile has a firm, fibrous texture, as well as being opaque in appearance. Recrystallization of the cellulose in the original lattice type occurs, and the shape mechanically imposed in the textile prior to treatment becomes the permanent shape of the yarn or fabric. This is by virtue of the fact that the fibers have been rendered strain-free in their new shape, as indicated above.

It might be expected that any shape imparted to noncrosslinked and unstiffened cotton textiles would be erased on wetting the textiles with water, which disrupts hydrogen bonds holding the cellulose chains together in any given shape. It is well known however that water penetrates cotton fibers only in the amorphous regions of the cellulose. Since the quaternary hydroxides of this invention appear to penetrate crystalline regions of each fiber as well as the amorphous regions, the plasticity induced by the quaternary hydroxide is to a considerable extent in regions not normally accessible to water. The plastic flow occurring in such regions under the influence of mechanical stress fixes the configuration or shape of the load-bearing elements in these regions. When the quaternary hydroxide is subsequently washed away, these regions recrystallize and again become inaccessible to water. The shape imparted in these regions is now remarkably durable to laundering and to mechanical tensioning in the wet as well as the dry state, inasmuch as these shaped regions are no longer accessible to water.

If the cotton textile is first wetted with the above quaternary ammonium hydroxides and subsequently placed in the desired shape, thus departing from the process disclosed herein, the shape imparted is far less durable than if the recommended sequence is followed. A possible explanation is that in shaping the yarn or fabric in the dry, unswollen state, more abrupt deformation and more highly localized mechanical strain can be impressed upon the unswollen fibers than is possible after they have already increased in diameter and shrunk in length as a result of being inflated with imbibed quaternary ammonium hydroxide solution. The sequence of operations specified in our invention favors the occurrence of plastic fiow and subsequent recrystallization of cellulose under conditions of high mechanical constraint of fibers. This suggests that plastic fiow and subsequent recrystallization occurring when the cellulose chains are forced into close aggregation has a greater effect in making an imposed shape durable, than does plastic flow and cellulose recrystallization occurring when the cellulose chains are greatly separated by swelling agent already imbibed. Thus the step of imposing the desired shape is accomplished when mechanically constricted regions of the fibers are made to undergo plastic flow. The step of fixation of shape is accomplished when the quaternary ammonium hydroxide is washed out of the fiber, causing cellulose recrystallization in the shaped, constricted regions of each fiber.

The relative inefiectiveness of alkali metal hydroxides in imparting durable shape to cotton textiles is probably due to failure of these hydroxides to decrystallize the cellulose within the fibers. The occurrence of several crystal lattice structures in soda cellulose is well established. The small size of alkali metal ions apparently enables them to fit into existing lattices or to form new lattice structures, as alkali cellulosates. The large size of the quaternary ammonium cations used in the present invention is probably essential in disrupting the lattice of cellulose I and preventing formation of new lattices related to cellulose II. As noted above, the quaternary ammonium cation must be above a certain minimum size, the tetramethylammonium cation being relatively ineffective in fixing shape previously imposed on the textile.

METHODS OF TEXTILE TESTING AND EVALUATION The examples that follow are illustrative of the processes of our invention. In testing coiled, treated yarn for the durability of the coiling or falsetwist, the recoverable stretch was taken as a measure of the degrees of coiling that remained. The recoverable stretch possessed by the yarn was measured by the following procedure. A yarn sample having a length of 15 inches when uncoiled was repeatedly stretched and relaxed, each stretching taking the yarn from the relaxed, coiled state to the trained, uncoiled state. The yarn was also smoothed repeatedly along its entire length by running it between two flat, adjacent surfaces. After 50 stretchings and 5 smoothings, the length of the yarn in the relaxed condition no longer increased with additional stretchings. At this point, just enough tension was applied to the yarn to completely straighten it and remove all coiling, and the percent elongation of the yarn in going from the relaxed, coiled state to the straightened condition was measured. Thus the measured stretch reflects only the recoverable stretch due to uncoiling of the yarn, but not 11 that due to stretching of fibers. When the yarn had no coiling, it showed zero recoverable stretch; but highly coiled yarn showed a high degree of recoverable stretch. The maximum elongation theoretically obtainable for 12/3 yarn coiled as tightly as possible about a 3.5 mm. rod was calculated to be 1600%. The measurements reported for dry yarn were made after the yarn Was equilibrated with air at room temperature and ordinary humidity. Measurements reported for wet yarn were made by repeatedly stretching and relaxing the yarn held fully immersed in a water bath at 25 C. After 50 stretchings and 5 smoothings, the length of the yarn in the relaxed state while immersed was noted, as Well as the yarn length in the straightened state while immersed. When redrying the yarn for further measurements, the sample was dried at the length it possessed when relaxed shrinkage. The coil was soaked in a given aqueous treating agent at room temperature for twenty minutes, was washed in water, soaked for five minutes in 1% aqueous acetic acid to remove any residual treating agent, was again washed in Water and was dried at 140 C. for ten minutes. The coil was then removed from the rod and air-equilibrated at room temperature and humidity. Yarn from runs 1, 2, and 3 was pliable, and windings of the coil showed no napping on separation during stretching of the coil. The yarn was white and free of discoloration in these three runs.

The following table gives the recoverable stretch of the treated yarn before and after successive rewetting and drying cycles. The amount of recoverable stretch observed is a measure of the degree of coiling retained in the yarn.

TAB LE I Reeoverable stretch, percent 2nd 3rd 4th Run N0. Treating agent 1 Dry 1 Rewet dry Rewet dry Rewet dry 1 B'1 A is benzyltrimethylammonium hydroxide TMA is tetramethylammonium hydroxide;

cuene is cupriethylenediamine.

2 The values for treated yarns prior to rewetting and redrying cycles. 3 windings fused together as cellulose dissolved.

and wet. The recoverable stretch was measured during repeated Wetting and drying cycles.

In testing durability of creases in fabric to repeated laundering, the procedure of the American Association of Textile Chemists and Colorists, Method 88C-l964T, Test III-C was used. This involved making appearance ratings under low angle lighting after five machine launderings and tumble dryings, using AATCC standard photographs as a basis for comparison, a rating of 1.0 corresponding to very low crease retention, and a rating of 5.0 corresponding to very high crease retention.

In measuring breaking strength across the creased regions of fabrics, the strength of strips one inch in width was measured in pounds by ASTM Method D39-49. The abrasion resistance of creased edges was determined by measuring the grab breaking strength across the crease before and after abrasion in the Accelerotor, the creased fabric sample having the twoflaps sewed together so as to expose the crease preferentially to the abrading collar.

All concentrations are expressed as parts by weight.

EXAMPLE 1 Imparting durable coiling to cotton yarn with benzyltrimethylammonium hydroxide A 15 inch length of scoured 12/3 cotton yarn was wound as a coil around a glass rod 3.5 mm. in diameter, no space being left between adjacent windings. Both ends of the coil were tied to the rod to prevent excessive These results show that 35-40% aqueous benzyltrimethylammonium hydroxide durably fixed a considerable degree of coiling in yarn. At a concentration as low as 30%, this agent was ineffective, however. Coiling fixed with sodium hydroxide, ethylenediamine, zinc chloride or mineral acids was not durable. Tetramethylammonium hydroxide imparted a low degree of durability. Cupriethylenediamine durably fixed a lower degree of coiling than did 35-40% benzyltrimethylammonium hydroxide.

It was also observed that when the coiled yarns prepared in runs No. .2 and 3 were immersed in boiling water, they became more tightly coiled than they were prior to immersion.

EXAMPLE 2 Effect of unwinding coiled yarn from mandrel prior to drying The procedure of Example 1, run No. 2, was repeated except that the coil of yarn was removed from the rod while still wet from the final water wash. The undried yarn was repeatedly stretched and relaxed until constant length was reached. The recoverable stretch before and after subsequent drying and rewetting cycles Was measured. Comparison of these values with the results of Example 1, run No. 2, is as follows:

TABLE II 1st 2nd 3rd 4th Wet, dr dry, dry, dry percent percent Rewet percent Rewet percent Rewet percent Coil unwound before 1st drying 6O 40 30 25 15 25 15 15 Coil unwound after 1st drying 1 45 35 25 20 15 15 1 Data from run 2 of Example 1.

13 These results show that after being subjected to three drying and rewetting cycles, the same amount of coiling was retained regardless of whether the coil were unwound before or after drying. Even after the first rewet- 14 tent to which cellulose I and crystalline lattice has been converted to the cellulose II lattice. The results were as follows:

TABLE III ting, the yarn unwound prior to the mural drying retained k B tWOdIhlI'dS as much COlllIlg as the yarn unwound after Time of ii drying. immersion lbs. I

EXAMPLE 3 Treating agent:

None None.-- 5. 8 0. 21 Effect of treating cotton yarn with benzyltrimethyl- 1 ammonium hydroxide prior to coiling the yarn Do: i e 511 I27 D .5 .28 A inch length of scoured 12/3 cotton yarn was D m. 2.3 .32 soaked slack for minutes in 35% aqueous benzyltri- 23% Neon methylammonium hydroxide. The greatly shrunken yarn lBTAiS y t methyla o hydroxide, q- Was strfitched 90% of Its 0118111211 t and Wound 15 The treated yarns were white and free from discoloraas a coil around a glass rod 3.5 mm. In diameter. 1t was tiom g q washeet soeked a water solutlon. contammge about These results show that even after 80 minutes con- 100 of acetic acid, again washed and dried at 140 C. for tact of the yam with benzyletrimethylammonium ffig Yarn was removed from the ee 20 droxide, there was no appreciable strength loss in the alr'egull ratlgn at e temperature e humlehty 1t yarn, and very slight conversion of cellulose I to cellu- Y e 3 to gi on f fi e z e lose II. Thus the quaternary ammonium hydroxides utilmgEan mg 0st e y a e 3 ized in the present invention cause no change in whitequa 1 'i g g ts were 2; ness, strength, or crystal lattice type in a cotton textile was e S m 0 aqueous .enzy tnme y e within the periods of time required for imparting shape momum hydroxide solution for 10 mlnutes, was coded to the textile around the rod without tension, and in the coiled state was further soaked in the 35% benzyltrimethylammonium EXAMPLE 5 hydroxide for 20 minutes, followed by the usual washing, a scouring, rewashing and drying procedure. The recoverig gg g i g g 2 23 3332? gg gi f g fi t gg able stretch in the dry yarn was 10%, in the rewet yarn y y y y m y e 5%, and in the subsequently redried yarn was zero. The procedure of run No. 3 of Example 1 was carried In a further experiment, yarn was soaked slack in out allowing various periods of time for soaking the yarn aqueous benzyltrimethylammonium hydroxide for 10 coil in the aqueous benzyltrimethylammonium hyminutes, andthe shrunken yarn was coiled under tension droxide. The effect of treating time on durability of coilaround the rod, so as to effect nearly complete restretch- 35 ing, as measured by recoverable stretch before and after ing, followed by soaking in the coiled state for 20 minsuccessive rewetting and drying cycles, was as follows:

TABLE Iv Recoverable stretch, percent Treating 2nd 3rd 4th Run No time, min. Dry Rewet dry Rewet dry Rewet dry 1 Same as mu 3 of Example 1.

utes in the 35% benzyltrimethylammonium hydroxide. The yarn was then washed, scoured, rewashed, and dried as usual. It was found to be considerably stiifened. The recoverable stretch in the dry yarn was 25%. In successive wetting and drying cycles, the recoverable stretch was 35% (wet), 10% (dry), 30% (rewet), 5% (redried), 25% (rewet) and 5% (redried). The amount of stretch in the dry state was very low, due apparently to the stiffness of the dry yarn.

These results show that treatment of the yarn with benzyltrimethylammonium hydroxide prior to coiling of the yarn fails to render the coiling as durable to mechanical tensioning as does the treatment of yarn already coiled.

EXAMPLE 4 Effect of benzyltrimethylammonium hydroxide and physical properties of cotton yarn Skeins of kierboiled 12/3 cotton yarn were immersed slack in 35% aqueous benzyltrimethylammonium hydroxide at room temperature for varying periods of time. The yarns were then washed free of benzyltrimethylammonium hydroxide, dried, and air-equilibrated. Their breaking strength and X-ray diffraction patterns were then determined. The ratio of heights of the IOT and 002 diffraction peaks, 1 1/1 is a measure of the ex- The results show that the durability imparted to coiling in cotton yarn increases as the time of contact with benzyltrimethylammonium hydroxide is increased. The increase in durability of yarn coiling in going from 20 minutes to 60 minutes contact time was only moderate, indicating that further prolonging of the treatment would have but minor effect on durability.

EXAMPLE 6 Use of trimethylolmelamine in dimensional stabilization of coiled yarn previously treated with benzyltrimethylammonium hydroxide The procedure of Example 1 was repeated, using various aqueous treating agents tabulated below. The washed and dried yarn coil, prior to removal from the rod, was then soaked in 20% aqueous trimethylolmelamine for 5 minutes at room temperature, was cured at C. for 5 minutes, washed for 5 minutes in hot running water, and dried at 140 C. for 5 minutes. The yarn was then unwound from the rod. Fibers of the treated yarn were insoluble in 0.5 M cupriethylenediamine but they greatly swelled and'ballooned in this reagent, indicating a very low degree 'of cellulose crosslinking had been imparted.

The degree of coiling retained in the yarn before and after successive rewetting and drying cycles may be seen from the recoverable stretch of the yarn, as reported benzyltrimethylammonium hydroxide treatment by itself, below: and the trimethylolmelamine treatment by itself, are

TABLE V Aqueous Recoverable stretch, percent treating agent Dry Rewet 2nd dry Rewet 3rd dry Rewet 4th dry Run No 1 BTA is benzyltrimethylammoniurn hydroxide, TMA is tetramethylammonium hydroxide, cuene is oupriethylenediamine.

2 The value for treated yarn prior to rewetting and redrying cycles.

These results show that the trirnethylolmelamine treatment by itself imparts little durability to coiling mechanishown. Results of using 10% DMEU in place of 2% trimethylolmelamine also are given.

TABLE VI Recoverable stretch, percent Treatment 1 Dry Rewet 2nd dry Rewet 3rd dry Rewet 4th dry Run No l V--- 35% BTA 180 45 35 25 2O 15 15 2% TMM 125 5 5 0 0 35% BIA, then 2% TMM 250 55 60 45 50 4O 40 35% BTA, then 10% DMEU. 130 45 20 15 15 10 1 BTA is benzyltrimethylammonium hydroxide; TMM is trimethylolmelamine.

cally set in yarn (run 1). Yet to yarn previously treated in coiled form with benzyltrimethylammonium hydroxide, it imparted great durability of coiling (run 2). The recoverable stretch retained after the fourth drying cycle in run 2 was twenty times that imparted by trimethylolmelamine alone, and eight times that imparted by benzyltrimethylammom'um hydroxide alone (run 2 of Example 1). Thus the combination of the two treatments imparted an eifect far greater than the sum of the elfects imparted by each treatment separately. Moreover after the first rewetting, there was little change in recoverable stretch or in yarn length during successive wetting and drying cycles, indicating a high degree of dimensional stabilization. The trimethylolmelamine was rendered highly effective even though applied in the absence of cellulose crosslinking catalysts.

The results also show that benzyltrimethylammonium hydroxide was far more efiective than sodium hydroxide, cupriethylenediamine or tetramethylammonium hydroxide in enhancing the dimensional stabilization subsequently imparted by trimethylolmelamine.

EXAMPLE 7 Use of trimethylolmelamine at low concentration on coiled yarn previously treated with benzyltrimethylammonium hydroxide The procedure of Example 1 was repeated using aqueous benzyltrimethylammonium hydroxide as the aqueous treating agent for the coiled yarn. The washed and dried yarn coil, prior to removal from the rod, was then soaked in 2% aqueous trimethylolmelamine for 5 minutes at room temperature, was cured at 140 C. for 5 minutes, and washed and dried as usual. The yarn was then unwound from the rod. Fibers of the treated yarn were insoluble in 0.5 M cupriethylenediamine, but they greatly swelled and ballooned in this reagent, indicating a very low degree of cellulose crosslinking had been imparted.

The degree of coiling retained in the yarn before and after successive rewetting and drying cycles may be seen from the recoverable stretch of the yarn, as reported below. For comparison, the results obtained from the The data show that the two treating agents, quaternary ammonium hydroxide and trimethylolmelamine, when used in succession had an efiect far greater than the sum of effects of each agent used separately, in rendering yarn coiling durable to stretching in both the wet and dry state of the yarn. Moreover, the trimethylolmelamine was eifective on the pretreated yarn even in absence of cellulose crosslinking catalysts. By contrast, the application of 1 0% DMEU to yarn previously coiled with benzyltrimethylammonium hydroxide produced no improvement in durability of coiling. Run 4 in which DMEU was cured on the coiled yarn, may be compared with run 1, in which no DMEU was used. The fibers of yarn treated in run 4 were almost totally insoluble in 0.5 M cupriethylenediamine, although greatly swollen by that reagent. This indicates a low degree of cellulose crosslinking had been imparted by the DMEU, in asmuch as fibers of the yarn treated in run 1 were soluble in the cupriethylenediamine. Yet the cellulose crosslinking produced by the DMEU was totally ineifective in stabilizing yarn coiling.

EXAMPLE 8 Use of tris(1-aziridinyl)phosphine oxide in dimensional stabilization of coiled yarn previously treated with benzyltrimethylammonium hydroxide The procedure of Example 1 was repeated using 35% aqueous benzyltrimethylammonium hydroxide as the aqueous treating agent for the coiled yarn. The washed and dried yarn coil, prior to removal from the rod, was then soaked in 4% aqueous tris(1-aziridinyl)phosphine oxide for 5 minutes at room temperature, was cured at C. for 5 minutes, washed for 5 minutes in hot running water, and dried at 140 C. for 5 minutes. The yarn was then unwound from the rod. Fibers of the treated yarn were insoluble in 0.5 M cupriethylenediamine, but they greatly swelled and ballooned in this reagent, indicating a very low degree of cellulose crosslinking had been imparted.

The degree of coiling retained in the yarn before and after successive rewetting and drying cycles may be seen from the recoverable stretch of the yarn, as reported 17 below. For comparison, the results obtained from the benzyltrimethylammonium hydroxide treatment by itself and the tris(1-aziridinyl)phosphine oxide by itself, are shown also.

18 EXAMPLE Imparting durable coiling to benzylated cotton yarn with benzyltrimethylammonium hydroxide A sample of 12/3 kierboiled yarn, which had been TABLE VII R Recoverable stretch, percent un No. Treatment 1 Dry Rewet 2nd dry Rewet 3rd dry Rewet 4th dry 1 35% BTA 180 45 35 25 20 15 2 4 125 5 5 5 0 3 35% BTA, then 4% APO 110 110 80 80 80 80 80 l BTA is benzyltrimethylammonium hydroxide; APO is tris(1-aziridiny])phosphine oxide.

Use of l,3-bis(hydroxymethyl) 4,5 dihydroxy-2-imidazolidinone in dimensional stabilization of coiled yarn previously treated with benzyltrimethylammonium hydroxide The procedure of Example 1 was repeated using 35% aqueous benzyltrimethylammonium hydroxide as the aqueous treating agent for the coiled yarn. The washed and dried yarn coil, prior to removal from the rod, was

of the yarn 'was wound as a coil around a glass rod 3.5

mm. in diameter. Both ends of the coil were tied to the rod to prevent excessive shrinkage. The coil was soaked in aqueous benzyltrimethylammonium hydroxide at room temperature for twenty minutes, was washed in water, soaked for five minutes in 1% aqueous acetic acid, was again washed in water, and was dried at 160 C. for 5 minutes. The coil was then removed from the rod and air equilibrated at room temperature and humidity.

For comparison, a second coil of the same benzylated yarn was simply heated at 160 C. for 5 minutes. The coiling durably imparted in each case was measured by determining the recoverable stretch of the two samples before and after repeated wetting and drying. Drying was at 85 C. for 5 minutes in all cycles but the first.

TABLE IX Recoverable stretch, percent Treatment Dry Rewet 2nd dry Rewet 3rd dry Rewet 4th dry 53%. 123 8 3 l"? .Ff .ff .1?

l BTA is benzyltrimethylammonium hydroxide.

The results show that benzyltrimethylammonium hydroxide was highly eifective in imparting durable coiling to yarn previously benzylated to a degree of substitution too low to have detectable thermoplasticity at the drying temperature used.

The results also show that the degree of coiling retained by BTA treated benzylated yarn in the 'wet state was much greater than in the dry state, and was much greater than the coiling retained in unbenzylated yarn in the wet state (see run 2 of Example 1), after treatment with 35% benzyltrimethylammonium hydroxide.

TABLE VIII Recoverable stretch, percent 7 Y W Treatment 1 Dry Rewet 2nd dry Rewet 3rd dry Rewet 4th dry Run No.:

l 35% BTA 18 45 35 25 20 15 15 35% BTA, then 20% dihydroxy DMEU-- 120 100 95 60 90 55 35% BTA, then 20% DMEU 10 9 40 80 30 50 20 BIA is benzyltrimethylammonium hydroxide.

The data show that after the fourth drying cycle, the EXAMPLE 11 yarn which had been aftercured with dihydroxy DMEU (run 2) retained nearly four times as much stretch as the yarn not aftercured with dihydroxy DMEU (run 1). On the other hand, yarn aftercured with DMEU in place of dihydroxy DMEU retained but little additional stretch (run 3).

Imparting durable creases in cotton print cloth with quaternary ammonium hydroxides Samples of x 80 desized, scoured, and bleached cotton print cloth were folded across the warp, and the folds were pressed with a steam iron to form creases. The fabric samples were then clamped between flat glass plates so as to maintain the folded and creased configuration, with the crease edge of each sample being even with the parallel edges of the upper and lower plates. The crease edge was wetted with a given aqueous quaternary ammonium hydroxide, and after standing for 10 minutes, the crease edge was immersed in running water. After 30 minutes washing, the plates were unclamped, and'the fabric dried for 10 minutes at 85 C. while in the folded and creased configuration,

The durability of the crease to five machine launderings and tumble dryings was evaluated by AATCC Method 88C-1964T, Test III-C described above. The creases were subsequently ironed as flat as possible in an attempt to remove them, and were again rated. The results were as follows:

TABLE X Crease rating (5 laun- Crease derings Concenrating and tration, (5 launironing Quaternary ammonium hydroxide percent derings) fiat) Benzytrimethyl 35 4. 5 4. 40 5. 0 4. 8 Benzylphenyldimethyl 36 4. 8 4. 2 48 5. 0 5. 0 Dibenzyldimethyl 39 4. 9 4. 1 52 0 0 1 4-x l lenebis triethyl 27 4 4 y y 35 4. a 4. 5 1,2-ethylenebis (benzyldimethyl) 25 3. 8 3. 0 33 4. 0 3. 6 None 3.0 2. 9

These results show that a high degree of durability of fabric creases to laundering and tumble drying was imparted, when the creases were treated with the quaternary ammonium hydroxides listed above.

The treated fabrics were free of discoloration. Their creases remained sharp and unaffected by 30 minutes immersion in boiling water.

EXAMPLE l2 Imparting durable creases to cotton twill with benzyltrimethylammonium hydroxide Samples of 94 x 40 bleached cotton twill were folded across the warp, and the folds were pressed with a steam iron to form creases. The fabric samples were then clamped between flat glass plates so as to maintain the folded and creased configuration, with the crease edge of each sample being even with the parallel edges of the upper and lower plates. The crease edge was wetted with aqueous benzyltrimethylammonium hydroxide, and after standing for 10 minutes, the crease edge was immersed in running water. After 30 minutes washing, the plates were unclamped and the fabric was ironed dry while in the folded and creased configuration. V

The durability of the creases to repeated laundering and tumble drying was determined by the AATCC Method 88C-1964T, Test III-C. The results were as follows:

TABLE XI Number of launderings Grease and dryings rating The treated twill was free of discoloration. Some puckering and stiffness were evident in the areas that had been treated with the benzyltrimethylammonium hydroxide.

The results show that a high degree of durability to laundering and tumble drying is imparted to creases in cotton twill, when the creases are treated with benzyltrimethylammonium hydroxide.

Grey twill similarly treated likewise showed greatly enhanced durability of creases previously ironed into the fabric, and the grey vat dye in the fabric showed no change in shade or hue as a result of the fabric treatment. Grey twill treated at the crease with 23% sodium hydroxide in place of benzyltrimethylammonium hydroxide showed considerably less durable creasing; moreover the dye shade and hue were considerably altered in the treated areas. The grey twill treated with benzyltrimethylammonium hydroxide showed some puckering and stiffness in the areas that had been treated with this reagent.

EXAMPLE 13 Removal of creases previously imparted to cotton fabric with aqueous benzyltrimethylammonium hydroxide A sample of 94 x 40 bleached cotton twill in which a crease had been set with benzyltrimethylammonium hydroxide as in Example 12 was unfolded at the crease, placed flat on a smooth surface and ironed to flatten the crease as much as possible. The crease still remained sharp however. The creased area was wetted with 40% aqueous benzyltrimethylammonium hydroxide, and after 5 minutes the fabric was thoroughly washed. It was then ironed dry. No crease remained. The fabric was white and free of discoloration.

A sample of x 80 print cloth in which a crease had been set with benzyltrimethylammonium hydroxide as in Example 11 was similarly ironed fiat, treated at the crease with 40% benzyltrimethylammonium hydroxide, was allowed to stand 5 minutes, washed and ironed dry. No crease remained. The fabric was white and free from discoloration. Properties of untreated fabric, fabric creased with quaternary ammonium hydroxide, and fabric in which the crease had been erased, were as follows:

These results show that the application of benzyltrimethylammonium hydroxide to render a crease durable did not significantly alter the strip break strength or the grab break strength across the crease. Re-application of the hydroxide to erase this crease likewise had no effect on strip breaking strength and little effect on grab breaking strength. These treatments also caused little change in the edge abrasion resistance of fabric as measured by the strength loss during edge abrasion. The loss in edge abrasion resistance caused by the creasing treatment was less than 6%, based on the strength loss in the untreated fabric during abrasion.

EXAMPLE 14 Effect of trimethylolmelamine on creases fixed in cotton fabric with benzyltrimethylammonium hydroxide Samples of 116 x 53 grey cotton twill were folded, given a crease, and the creases were treated with 40% aqueous benzyltrimethylammonium hydroxide by the procedure of Example 12. Subsequently the Washed and dried samples were wetted along the crease with an aqueous solution of trimethylolmelamine. The solution was applied in the area bounded by the crease and extending one inch from the crease. The fabric was wrung to remove excess solution, and was oven cured at C. for 5 minutes while being maintained in the folded and creased configuration. It was then washed, dried and air-equilibrated. The properties obtained at various concentrations of trimethylolmelamine (TMM) are listed below.

Grab break strength pounds 1 Very sharp=10, rounded=1.

2 Fabric not treated with benzyltrimethylammonium hydroxide after being creased.

3 Greased, untreated.

The data show that the trimethylolmelamine prevented stiffening and puckering normally caused by the prior use of benzyltrimethylammonium hydroxide, and increased the sharpness of creases retained on washing the fabric. The grab breaking strength obtained was 93-98% of that shown by fabric treated only with benzyltrimethylammonium hydroxide, and 92-97% of that shown by untreated fabric. Thus the trimethylolmelamine applied in the absence of catalyst caused almost no loss of breaking strength.

The data also show that under the conditions used, trimethylolmelamine was ineffective in rendering creases durable if the benzyltrimethylammonium hydroxide treatment was omitted.

We claim:

1. A method of imparting a durable configuration to a fibrous cellulosic material, comprising:

(a) mechanically fixing the cellulosic material into an ultimately desired configuration;

(b) impregnating the cellulosic material, while in the thus-fixed configuration, for about from 1 to 60 minutes at a temperature of about from 15 C. to 35 C. with an aqueous solution containing about from 33% to 60% by weight of a quaternary ammonium hydroxide having the structural configuration Rr-QCHrIII-Rs OH- $113 TCHr-CHz-IIFCHz-Q H- and R is a radical selected from the group consisting of hydrogen and one having the structural configuration (0) Washing the thus-impregnated cellulosic material to remove any unreacted quaternary ammonium hydroxide and drying it; and

(d) releasing the dried cellulosic material from its fixed position to obtain it in the desired imparted configuration.

2. A method of imparting a durable configuration to a fibrous cellulosic material, comprising:

(a) mechanically fixing the cellulosic material into an ultimately desired configuration;

(b) impregnating the cellulosic material, while in the thus-fixed configuration, for about from 1 to 60 minutes at a temperature of about from C. to 35 C. with an aqueous solution containing about from 33 to 60% by weight of a quaternary ammonium hydroxide selected from the group consisting of benzyltrimethylammonium hydroxide, dibenzyldimethylammonium hydroxide, phenyldimethylbenzylammonium hydroxide, p xylylenebis(triethylammonium) hydroxide, and 1,2-ethylenebis(benzyldimethylammoni um) hydroxide;

(c) washing the thus-impregnated cellulosic material to remove any unreacted quaternary ammonium hydroxide and drying it; and

(d) releasing the dried cellulosic material from its fixed position to obtain it in the desired imparted configuration.

3. The method of claim 2 wherein the fibrous cellulosic material is a cotton yarn and the ultimately desired and imparted configuration is a coil.

4. The method of claim 2 wherein the fibrous cellulosic material is benzylated cotton yarn having not more than one benzyl group attached to the cotton cellulose through either linkage for every three anhydroglucose units of the cellulose and the ultimately desired and imparted configuration is a coil.

5. A method of imparting a durable crease to a Woven fibrous cellulosic fabric, comprising (a) pressing a crease into the fabric;

(b) mechanically positioning the creased fabric so as to maintain the crease therein;

(0) impregnating the crease edge of the thus-positioned fabric for about from 1 to 60 minutes at a temperature of about from 15 C. to 35 C. with an aqueous solution containing about from 33% to 60% by weight of a quaternary ammonium hydroxide having the structural configuration RrQ-CHr-lTI-Ral onwherein R and R are radicals selected from the group consisting of methyl, ethyl, phenyl, and benzyl, R is a radical selected from the group consisting of methyl, ethyl, and one having the structural configuration and R is a radical selected from the group consisting (d) washing the impregnated, creased edge of the fabric to remove any unreacted quaternary ammonium hydroxide; and

(e) releasing the washed, creased fabric from its mechanical positioning, and drying the released fabric to obtain a fabric having the crease set therein.

6. A method of imparting a durable crease to a woven fibrous cellulosic fabric, comprising (a) pressing a crease into the fabric;

(b) mechanically positioning the creased fabric so as to maintain the crease therein;

(c) impregnating the creased edge of the thus-positioned fabric for about from 1 to 60 minutes at a temperature of about from 15 C. to 35 C. with an aqueous solution containing about from 33 to 60% by weight of a quaternary ammonium hydroxide selected from the group consisting of benzyltrimethylammonium hydroxide, dibenzyldimethylammonium hydroxide, phenyldimethylbenzylammonium hydroxide, p-xylylenebis(triethylammonium) hydroxide, and 1,2-ethylenebis(benzyldimethylammonium) hydroxide;

(d) washing the impregnated, creased edge of the fabric to remove any unreacted quaternary amomnium hydroxide;

(e) releasing the washed, creased fabric from its mechanical positioning, and drying the released fabric to obtain a fabric having the crease set therein.

7. The method of claim 6 wherein the woven fibrous cellulosic fabric is cotton fabric.

8. The product produced by the process of claim 3.

9. A method for imparting stabilized coiling and increased dimensional stability to the coiled cotton yarn defined by claim 8, comprising (a) impregnating the yarn coil, while mechanically holding it in its coiled configuration, with an aqueous solution containing about from 2% to 30% by weight of a polyfunctional compound selected from the group consisting of trimethylolmelamine, tris(l-aziridinyl) phosphine oxide, and 1,3-bis (hydroxymethyl)-4,5- dihydroxy-2-imidazolidinone;

(b) heating the impregnated yarn coil for about from 2 to 30 minutes at a temperature of about from 120 C. to 170 C. while maintaining the yarn in its coiled form, to drive off water and induce polymerization as well as a low degree of cellulose crosslinking;

(c) Washing the thus-heated yarn coil to remove unreacted reagents, drying it, and releasing it from its mechanical holder.

10. The product produced by the process of claim 4.

11. A method for imparting stabilized coiling and increased dimensional stability to the coiled benzylated cotton yarn defined by claim 10, comprising (a) impregnating the yarn coil, while mechanically holding it in its coiled configuration, with an aqueous solution containing about from 2% to 30% by weight of a polyfunctional compound selected from the group consisting of trimethylolmelamine, tris( 1- aziridinyl)phosphine oxide, and 1,3-bis (hydroxymethyl) -4,5-dihydroxy-2-imidazolidinone;

(b) heating the impregnated yarn coil for about from 2 to 30 minutes at a temperature of about from 120 C. to 170 C. while maintaining the yarn in its coiled form, to drive off water and induce polymerization as well as a low degree of cellulose crosslinking;

(c) washing the thus-heated yarn coil to remove unreacted reagents, drying it, and releasing it from its mechanical holder.

12. The product produced by the process of claim 7.

13. A method of removing the set crease in the woven fibrous cellulosic fabric defined by claim 12, comprising (a) ironing the crease to flatten it;

(b) impregnating the flattened crease for about from 1 to 60 minutes at a temperature of about from 15 to 35 C. with an aqueous solution containing about from 33% to 60% by weight of a quaternary am- 24 monium hydroxide having the structural configuratron R1 m{ CH2l IRa 0H- wherein R and R are radicals selected from the group consisting of methyl, ethyl, phenyl, and benzyl, R is a radical selected from the group consisting of methyl, ethyl, and one having the structural conand R is a radical selected from the group consisting of hydrogen and one having the structural configuration (c) washing the impregnated, flattened crease to remove any unreacted quaternary ammonium hydrox ide, and drying the washed crease to obtain a fabric Without the crease.

14. A method of removing the set crease in the woven fibrous cellulosic fabric defined by claim 12, comprising (a) ironing the crease to flatten it;

(b) impregnating the flattened crease for about from 1 to 60 minutes at a temperature of about from 15 C. to 35 C. with an aqueous solution containing about from 33% to 60% by weight of a quaternary ammonium hydroxide selected from the group consisting of benzyltrimethylammonium hydroxide, dibenzylammonium hydroxide, phenyldimethylbenzylammonium hydroxide, p xylylmethylenebis(triethylammonium) hydroxide, and 1,2-ethylenebis(benzyldimethylammonium) hydroxide;

(c) washing the impregnated, flattened crease to remove any unreacted quaternary ammonium hydroxide, and drying-the washed crease to obtain a fabric without the crease.

15. A method of enhancing the sharpness of the set 'crease in the product defined by claim 12 and of eliminating stilfness and puckering in said crease, comprising (a) impregnating the crease, while mechanically holding the fabric so as to maintain the crease therein, with an aqueous solution containing about from 2% to 30% by Weight of a polyfunctional compound selected from the group consisting of trimethylolmelamine, tris(1-aziridinyl)phosphine oxide, and 1,3- bis(hydroxymethyl)-4,5-dihydroxy 2 imidazolidinone;

(b) heating the impregnated mechanically held, fabric crease for about from 2 to 30 minutes at a temperature of about from C. to C. to drive off water and induce polymerization as well as a low degree of cellulose crosslinking;

(c) washing the thus-heated fabric crease to remove unreacted reagents, drying it, and releasing it from its mechanical holder.

References Cited Reeves et al.: American Dyestulf Reporter, vol. 48, No.21, pp. 43-50 (1959).

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner U.S. Cl. X.R. 

